1. Field of the Invention
This invention relates to an exhaust system for two-stroke cycle internal combustion engines, which system comprises a diffuser, which is adapted to be connected to the internal combustion engine, a baffle, which is provided downstream of the diffuser, a catalytic converter, which is disposed between said diffuser and said baffle, and a diffuser discharge pipe, which extends in said diffuser and is much smaller in diameter than the largest diameter of the exhaust system.
2. Description of the Prior Art
The polluant contents of exhaust gases must meet certain legally prescribed requirements and are usually determined during a cycle of operations including a cold start and idling periods. Said requirements cannot be met unless the catalytic converter can be lighted off quickly. If the catalytic converter succeeds a diffuser, which is required to ensure the desired effects of gas dynamics, the catalytic converter will be spaced a large distance apart from th internal combustion engine in a region in which the temperatures of the exhaust gas are so low that the temperature at which the catalytic converter will be lighted off will be reached only a considerable time after the cycle of operations has been initiated. The baffle serves to reflect the pressure waves so that the change of the cylinder charge will be promoted.
In an exhaust system which is of the kind described first hereinbefore and has been disclosed in U.S. Pat. No. 4,206,177, the diffuser discharge pipe extends into the diffuser only over a relatively short distance and the catalytic converter is wound around the downstream end portion of said discharge pipe. As a result, the exhaust gases do not enter the catalytic converter through the diffuser discharge pipe but must flow radially through the catalytic converter into the discharge pipe. That arrangement will by no means ensure that the catalytic converter will be lighted off quickly.